Hey, i just starting to get knowledge how to create workouts, getting familiar with Zones and what is happening in each of them.
There is one thing that is bothering me for a while.
Theory says that: if you’re training in Zone 1 and Zone 2 (up to first lactate threshold) your body gets fuel from fat, and you’re also training body to posses more energy from fat as possible. If you’re training in higher Zones, then your body is switching in to producing energy from carbohydrates.
For example: If in training workout i will spend 1h in Zone 1 or Zone 2, then i’ll make several intervals in Zone 6 and again return to Zone 1 for 1h.
My questions is: will body also switch back go gain energy from fat after intervals. Or maybe once switched to carbohydrates will no longer return to fat? Does source of energy depends only up to heartrate and intensivity?
Hey,
The fuel your body is using during exercise is a combination of the two. At which relation the two fuels (fat and carbohydrates) are used is dependent on the intensity and the duration of the activity (mostly intensity).
At very high intensity (the intervals that you are describing) all the energy comes from carbohydrates (or almost all 95-100%). When you then go back to riding at zone 1, your body will switch to fat and will burn more fat in comparison to carbohydrates (but there is always some carbohydrates being burned during zone 1+2).
Some suggest that after the intervals your body will also burn the lactate produced during the intervals before (or in addition) to burning the other two energy sources.
To conclude: low intensity = more fat burning, high intensity = more carbohydrates burning.
There is no on/off switch. Instead there is a slope where fats reduce and carbs increase. Intensity drives demand, so the harder you go, the more the demand for CHO. The crossover point where it’s about 50-50% differs based on how well-trained your are.
@Michal_Iwancewicz, as an example that the body is drawing energy from anaerobic source even at rest is the fact of resting lactate. A metabolically healthy person will be ≤ 1mmol at rest. An unhealthy person might be ≥ 2mmol at rest. Side note, cardiac muscle is especially keen to burn lactate as a fuel.
Dr San Millán has indicated several times that once the body has begun to primarily draw fuel anaerobically in a training session it won’t return the the same aerobic burning as was occurring prior to the ‘crossover’. This is why he puts any ≥Z3 work at the end of his sessions.
The answer, in short, to your question, is no. As already said, there is no on/off switch. Isolate the zones as much as possible in training. On an endurance ride you typically do not want to be doing Z6 efforts.
Yes, your right that those should not be joined in one workout. It was just question to show idea. Thanks to graphic @Gerald everything is well explained. Thank you!
